Resistance heater graphite test capsule

ABSTRACT

A test capsule of a graphite material which includes a cylindrical bottom part and a cover which is engageable over the bottom part and which includes either a spherical engagement surface which is engageable with a partially spherical engagement surface of the bottom part or a conical surface of the bottom part. The cover and the bottom part are provided with ring-shaped ends which are engageable by electrodes for supplying current therethrough for resistance heating thereof in order to heat the sample within the cylindrical bottom part container.

United States Patent [1 1 Kraus RESISTANCE HEATER GRAPHITE TEST CAPSULE[75] Inventor: Thaddaus Kraus, Furstentum,

Liechtenstein [73] Assignee: Balzers Patent und BeteiligungsAktiengesellschaft, Balzers, Furstentum, Liechtenstein [22] Filed: July6, 1971 [21] Appl. No.: 159,837

[30] Foreign Application Priority Data July 15, 1970 Switzerland10790/70 [52] US. Cl. 73/19, 13/20, 219/427 [51] Int. Cl. G0ln 7/00 [58]Field of Search 73/19; 219/427;

[5 6] References Cited UNITED STATES PATENTS 1,981,015 11/1934 Williams..2l9/427 [111 3,751,965 Aug. 14, 1973 2,749,424 6/1956 Dieterich 13/252,945,756 7/1960 Ballantine... 13/25 3,371,142 2/1968 Soller 219/427FOREIGN PATENTS OR APPLICATIONS 461,141 10/1968 Switzerland 219/20Primary Examiner-Herbert Goldstein AttorneyJohn J. McGlew et a1.

[ 7 ABSTRACT 2 Claims, 3 Drawing Figures PAIENIE AUG 1 4mm FIG! FIGZ

INVENTOR. THADDAUS K RAUS O R NEY '1 RESISTANCE HEATER GRAPHITE TESTCAPSULE BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates in general to devices employed for the examination ofsamples particularly for the analytical determination of their gascontent and in particular to a new and useful resistance-heater testcapsule made of graphite which includes a lower cylindrical part and acover having either spherical or conical engagement surfaces.

2. Description of the Prior Art The present invention is used in theexamination of samples, particularly for the analytical determination oftheir gas content. A method is known where the sample to be examined isenclosed in a small container made of a graphite material which isclamped between two electrodes and which is heated by resistance heatingby the passage of direct current therethrough. The gases given offduring the heating of the sample diffuse through the container wall andare fed to a measuring instrument for determination of their type andamount. A device of this type is described in detail in U.S. Pat. No.3,683,699 dated Aug. 15, 1972.

For this testing purpose there is employed a two-part test capsule whichcomprises a lower part and a cover. If the cover and the lower part donot have precise dimensions they can be exactly interengaged. Theengageable surface dimensions can vary for example, when the parts arewarped by the pressing of the coal powder during the graphitization, orif the clamping electrodes are not accurately aligned. This causesdifficulties due to the fact that either the electric contact betweenthe damped ends of the capsule and the electrode becomes defective, orthat the two parts of the capsule no longer close tightly. In the firstcase the effeet is excessive heating at the contact points with theresult of uneven heating of the capsule. In this other case in which theparts do not close tightly a part of the test melt can escape throughthe opening between the parts. Both yield errors in the measuringresult.

SUMMARY OF THE INVENTION The present invention overcomes the difficultyof the prior art by providing a capsule which includes a cylindricalbottom part which interengages with a cover and wherein the engagementsurfaces are either partially spherical or conical. A test capsule whichis made of graphite is constructed'so that it can be clamped between twocurrent supply electrodes and heated by direct current passage. Bymaking the engagement surfaces of the two parts either conical orspherical they may be pivoted relative to each other during the closing.This pivotability permits the lower part and the cover to hug theclamping electrodes tightly during the clamping and even if they are notaccurately aligned insures a jointless seal in each position between thecover part and the capsule body. In addition, the use of a cover with aclosing surface in the form of a partial spherical surface compensatesthe unavoidable inaccuracies in the manufacture of the capsule. Even ifthe parts are warped during the graphitization, this has only a minoreffect.

Accordingly it is an object of the invention to provide an improvedcapsule for determining the gas content of materials which includes agraphite cylindrical capsule which is closed by a cover of graphite andwhich are constructed to be engaged by current electrodes for thepassage of a current therethrough, and which includes engagementsurfaces which are either spherical or conical so that they may be movedrelative to each other during the clamping in order to maintain a tightinterengagement and closing of the capsule.

A further object of the invention is to provide a test capsule which issimple in design, rugged in construction and economical to manufacture.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its uses,reference should be had to the accompanying drawing and descriptivematter in which there are illustrated preferred embodiments of theinvention.

IN THE DRAWING FIG. I is an exploded sectional view of a capsuleconstructed in accordance with the invention;

FIG. 2 is a top plan view of a capsule and cover shown in FIG. 1; and

FIG. 3 is an exploded view similar to FIG. 1 of another embodiment ofthe invention.

GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to thedrawings in particular the invention embodied therein in FIGS. 1 and 2comprises a capsule generally designated 10 which includes a lower partor cylindrical receptacle 1 and a top part or cover 2. The lower part 1and the top part 2 include engagement surfaces 3 and 4 which in theembodiment of FIGS. 1 and 2 are made with spherically shaped surfaces ofthe same radius of curvature so that when they interengage one part canbe pivoted relative to the other without the tight closing connectionbeing broken. The top part 2 includes an annular flange 5 and the bottompart 1 includes an annular flange 6 moving clamping ends which areengaged with electrodes for the passing of a heating current through theelectrodes into the capsule which is closed in operation.

The two spherical form surfaces provide during the closing of thecapsule an areal seal, providing a particularly reliable seal. It can beseen that it suffices if only the surface portions of the lower part andthe cover coming in contact with each other represent parts of sphericalsurfaces. The central portion 7 of the surface of the cover facing thecapsule in the closed state which does not come in contact with thelower part can therefore be flat if desired.

It is not necessary that the two parts of the capsule have the usualform of the larger lower part and a smaller cover, as is shown in FIGS.1 and 2. Rather the separating surfaces between the two parts can alsobe arranged in the'proximity of the center plane of the cylindricalcapsule. For example: the two halves of the capsule can be producedfirst by pressing as graphite parts of the same form and size, and thespherical surfaces can then be obtained by milling or grinding. This waythere is obtained a capsule which may close exactly. In addition, thecosts are reduced in the produc- In the embodiments of FIGS. 1 and 2,the ends and 6 are of ring-shaped form. A central depression 5a, 6a areformed in cover 2 and in the receptacle respectively. This insures thatthe heat flow through the clamping element is reduced. However planecontact surfaces without depressions can also be used if desired.

As indicated in FIG. 3 the contacting surfaces 3 and 4 may be madeconical for capusles having a bottom part 1' and a cover 2.

As closing surfaces have been designated within the framework of thisspecification the surface portions of the lower part 1 and the cover 2facing each other form a jointless seal during the closing of thecapsule. As-the embodiments show the closing surfaces need not be thesame as the contact surfaces. It suffices rather that if the closingsurfaces touch each other at several points,

for example, along a closed sealing line in such a way that a tight sealfor the test melt is obtained it is sufficient. I

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be un derstood that the invention may be embodiedothertheir outer end for clamping these parts between current supplyelectrodes for being heated by current passage therethrough, said coverand said lower part having smooth relatively slideable engagementsurfaces with each of said engagement surfaces being spherical, saidcover being rotatable about the axis of said cylindrical part and beingtiltable about an axis perpendicular thereto to permit the movement ofsaid parts to effect centering and closing contact between theengagement surfaces.

2. A test capsule made of a graphite material for examining samplesaccording to a hot extraction method wherein the capsule is clampedbetween electrodes and comprises an electrical resistance heater,comprising a cylindrical graphite container having a closed end with anend wall having an exterior face with a central recess and an encirclingrim around the recess defining a first electrode connection end, saidcontainer having an opposited opened end with a rim defining a sphericalengagement surface, a cover having a spherical engagement surfaceengaged on said rim in pivotal sliding engagement with the surface ofsaid rim, said cover having an opposite exterior face with a secondelectrode connection, said cover being rotatable about the axis of saidcontainer and also being tiltable with respect to the axis of saidcontainer in order to permit the container and the cover to adaptthemselves to the position of the clamping electrodes whereby tofacilitate an improved current flow therethrough.

1. A test capsule made of a graphite material for examining samplesaccording to a hot extraction method comprising a lower cylindrical partand a cover, said cover and said lower cylindrical part having means attheir outer end for clamping these parts between current supplyelectrodes for being heated by current passage therethrough, said coverand said lower part having smooth relatively slideable engagementsurfaces with each of said engagement surfaces being spherical, saidcover being rotatable about the axis of said cylindrical part and beingtiltable about an axis perpendicular thereto to permit the movement ofsaid parts to effect centering and closing contact between theengagement surfaces.
 2. A test capsule made of a graphite material forexamining samples according to a hot extraction method wherein thecapsule is clamped between electrodes and comprises an electricalresistance heater, comprising a cylindrical graphite container having aclosed end with an end wall having an exterior face with a centralrecess and an encircling rim around the recess defining a firstelectrode connection end, said container having an opposited opened endwith a rim defining a spherical engagement surface, a cover having aspherical engagement surface engaged on said rim in pivotal slidingengagement with the surface of said rim, said cover having an oppositeexterior face with a second electrode connection, said cover beingrotatable about the axis of said container and also being tiltable withrespect to the axis of said container in order to permit the containerand the cover to adapt themselves to the position of the clampingelectrodes whereby to facilitate an improved current flow therethrough.